1. Field of the Invention
This invention pertains to tone mapping of high dynamic range images, and specifically to tone compression by multi-scale homomorphic filtering using incrementally-spaced adaptation levels weighted by a diminishing factor and applying restored visual cues.
2. Related Background Art
The human eye has a large dynamic range and is capable of dynamically adjusting to a portion of a scene that is only 1/10,000 as bright as the brightest point in the field of view. Present day technology can create image files that have this high dynamic range (HDR), and such images have become useful in many industries, including medical and computer-generated imagery. However, most computer display and printing devices are limited to a useful dynamic range of about 100:1, much less than the range of luminance values of an HDR image.
Tone mapping techniques can compress the dynamic range of HDR images for viewing on a standard, low dynamic range device, but current techniques have drawbacks. Most of these techniques use a single adaptation level or, alternatively, a small set of arbitrary adaptation levels, which are expensive in terms of processing speed. In addition, the resultant images often are plagued by edge and halo artifacts, lack a realistic look, appear unnaturally illuminated, or lack clarity. Finally, the quality and effectiveness of the results of these techniques are often dependent on the content of the original HDR image and must be adjusted on a per-image basis.